As infrastructure of network has developed, cloud computing services grow up. There are several kind of services related to cloud computing, cloud storage service has more special characteristic. In the cloud storage service, users’ data are stored in the cloud servers exist on somewhere. If the data stored in the server is leaked, this can cause financial damage. In company, therefore, they do not use cloud storage service at all, use their private cloud server, or limit the use for less important data.Cloud storage services protect users’ data by encryption. Some services use server-side encryption. The others use client-side encryption. However, each method has limitations and need more secure method.In this paper, we suggest a method to prevent leakage of data from server-side by encrypting data on the client. Also the method prevents leak of data and encryption key from client-side based on TPM.